8519: link is as bear

link, a famous bear magician in Bear Institute of Talented(BIT), has recently learned new magic.

That is, given a array a containing n elements a1,...,an, and link can cast the following magic:

link can choose two integers l,r such that $1\le l\le r\le n$, making all ai=xor(l,r) where $l\le i\le r$ and xor(l,r) denotes the bitwise-xor of all elements in $[l,r]$. More formally, xor(l,r)=al⊕al+1⊕...⊕ar.

link can cast this magic any time(possibly, zero) and can choose l,rarbitrarily. However, since link has a sort of Obsessive-Compulsive Disorder(OCD), he wants all elements to become the same after his operation. Now, he wonders about the maximum of this same value.

What's more, link finds that the given array has a weird property: there always exists at least one pair of $x！=y)$ such that ax=ay.

The first line contains an integer T(1≤T≤3∗104), the number of the test cases.

The first line of each test case is an interger n(1≤n≤105), the length of the array a.

The second line of each test case containing n integers, while the $i$-th denoting ai(0≤ai≤1015). It's guaranteed that there always exists at least one pair of $y(x！=y)$ such that ax=ay.

It's also guaranteed that Σn≤106.

2
5
10 10 10 10 10
4
1 1 2 1

10
3